This invention relates to implantable devices for promoting tissue growth or tissue expansion, and more particularly to a fluid expandable prosthetic device that does not require a valving arrangement for the infusion or removal of fluid.
Tissue expansion devices have long been used to produce a flap of skin for covering or accommodating a prosthetic device. The skin flap is usually formed at or adjacent to a designated area that has been structurally deformed or superficially altered due to illness, accident or surgery, for example.
The process of tissue expansion often begins by subcutaneously implanting a tissue expander, in a contracted condition, at a selected location. The tissue expander is gradually enlarged by the infusion of fluid into a fluid chamber of the expander.
The infusion process is usually accomplished through a fluid inlet valve arrangement that is directly or indirectly connected to the tissue expander chamber. For example, U.S. Pat. No. 4,190,040 discloses a tissue expansion device with a resealable fluid inlet valve that is connected to the expansion device via a connection tube.
The term "valve arrangement" as used herein is intended to refer to a predetermined path of fluid flow from a fluid inlet valve into a tissue expander chamber through an entry port of the chamber, and also contemplates a fluid flow conduit connecting the entry port to the fluid inlet valve. The term "entry port" as used herein refers to a predetermined fluid inlet opening in a tissue expander chamber and also contemplates an opening defined by a fluid inlet valve.
Other tissue expansion devices, such as shown in U.S. Pat. Nos. 4,217,889 and 4,643,733 include valving arrangements that are connected directly or indirectly to the expansion chamber by means of a tube or other similar passageway.
Tissue expanders with valve arrangements normally require surgical implantation of the tissue expander portion of the device, the fluid inlet valve and any connection tube that joins the valve to the expansion chamber. The extensiveness of the implant surgery thus corresponds to the size and extent of the tissue expander and its accompanying valve arrangement and conduit.
Ordinarily, the access portion of a fluid inlet valve is of substantially less size than the tissue expansion chamber, and represents a relatively small target area in which to insert a needle for infusing or withdrawing fluid. Since repetitive infusions are usually required to accomplish a desired tissue expansion, the skin in the area of the infusion valve often becomes sensitized due to frequent penetrations by an infusion needle in a predetermined small area.
A further problem inherent in the use of tissue expansion devices that have valve arrangements connected to the tissue expansion chamber is the surgical scope of a removal operation when the tissue expansion device is to be withdrawn. The removal operation requires an incision that is large enough to extract both the tissue expansion chamber and the valve arrangement, and is generally of similar extent to the surgery used in installing the tissue expansion device and valve arrangement.
It is thus desirable to provide a tissue expansion device which does not require a valve arrangement for the intake or removal of fluid, and which can be installed with a relatively small surgical incision.